/Engine/Source/Runtime/Core/Public/Misc/Base64.h
Encodes aFStringinto a Base64 string
A string that encodes the binary data in a way that can be safely transmitted via various Internet protocols
static [FString](API\Runtime\Core\Containers\FString) Encode ( const [FString](API\Runtime\Core\Containers\FString) & Source, EBase64Mode Mode )